Refrigeration is an important utility for chemical, food and pharmaceutical manufacturing as well as other material processing industries. Generally refrigeration is generated using a vapor compression refrigeration circuit wherein a refrigerant fluid is compressed, cooled, expanded to generate refrigeration and then warmed to supply refrigeration to a refrigeration load.
While some refrigeration loads have a relatively unvarying refrigeration requirement, many refrigeration loads have refrigeration requirements which increase and decrease with time. In the interest of efficiency, it is desirable to vary the amount of refrigeration supplied to the refrigeration load to match the refrigeration requirements of refrigeration loads which have unsteady refrigeration requirements.
One way of addressing this problem is to adjust the refrigeration output of the refrigeration circuit by modulating the circulation rate of the refrigerant fluid within the refrigeration circuit. Unfortunately, refrigeration circuits are most efficient when operated continuously and at or near their maximum capacity. Another way of addressing this problem is to use a cryogenic liquid such as liquid nitrogen or liquid carbon dioxide to augment, as needed, the refrigeration provided by the refrigeration circuit to the refrigeration load. However, this expedient is quite costly owing to the costs of the cryogen.
Accordingly, it is an object of this invention to provide a system for efficiently providing refrigeration to a refrigeration load which has varying refrigeration requirements.